Surveillance imaging following colon cancer resection: Universal or risk-based?

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307 Background: Current colon cancer surveillance guidelines recommend annual imaging for all patients following curative resection. The primary aim of this study is to evaluate variation in surveillance practices following colon cancer resection. Methods: A retrospective cohort study of patients ≥ 66 years old with stage I-III colon cancer that underwent surgical resection in the Surveillance, Epidemiology, and End Results-Medicare linked database (July 2001 through December 2007) with at least 3 years of follow-up was performed. Medicare claims for PET and CT scan of the chest, abdomen and pelvis performed after surgical resection were recorded and analyzed. In order to evaluate the use of definitive treatment (DT) for presumed recurrent disease, we identified patients who had undergone lung, liver, or colorectal resection during follow-up. Results: Of 22,544 patients who underwent primary resection of colon cancer, 13,753 (61.0%) underwent PET and/or CT after resection and 1,109 (4.52%) underwent at least 1 DT. The mean number of imaging performed for patients who did not undergo DT was 1.68. Within this group, the utilization of PET and/or CT varied by stage, with 14.1%, 22.4%, and 42.2% of patients with stage I, II, and III disease undergoing imaging, respectively. The most significant factor associated with PET and/or CT was tumor stage with an odds ratio of 1.86 (95% CI 1.70-2.02, P<0.001) for stage II disease and 4.56 (95% CI 4.17-4.99, P<0.001) for stage III disease compared to stage I disease. Additional factors significantly associated with PET and/or CT included year of diagnosis and SEER region. Among patients who did undergo DT, the mean number of PET and/or CT performed was 5.37 but the majority of imaging studies were performed 4 months prior to DT (mean 2.95). Conclusions: There is a high degree of variation in the use of surveillance imaging among elderly patients with localized colon cancer although some of this variation appears to be associated with stage at presentation. Our findings highlight discordance between clinical practice and surveillance guidelines. Further study is needed to understand the basis and appropriateness of clinical decision making that departs from guideline-based care.